Use pgrep instead of pidof and ps -C
Use /bin/sh instead of /bin/bash as the default shell.

These changes make the plugin compatible with other unix-like
OS (*BSD, OSx, etc).
Also, using pgrep removes the need to check for different uwsgi
process names.
Merge pull request #3 from WuShell/master

Use pgrep instead of pidof and ps -C